More than one year prior to the filing date of this invention, the applicant designed and sold a triangular-shaped sound reproduction speaker generally illustrated in FIGS. 1-6.
Such prior art sound reproduction speaker, generally designated with the numeral 20, has an isosceles shaped enclosure 22 having a front wall 24, a rear wall 26, an isosceles side wall 28, an isosceles side wall 30 and a width side wall 32. Side walls 28 and 30 merged at an apex 34 having an angle of approximately 90.degree.. The intersection of side walls 28 and 30 with the side wall 32 form corners 36 and 38 respectively each having an angle of approximately 45.degree.. Additionally the height between the apex 34 and a normal distance to the side wall 32 was less than the width as defined by the length of the side wall 32.
The speaker 20 has a front mid-to-low frequency range sound reproduction element or driver 40 mounted in the front wall 24. Such sound reproduction element 40 is of a direct radiation, diaphragm type driver having a permanent magnet used in operation with a voice coil for driving the diaphragm.
Additionally the speaker 20 has a rear low-to-mid frequency range sound reproduction element or driver 44 of the same type as element 40. The rear driver 44 is mounted in the rear wall for creating and producing sound waves directed outward from the rear wall 26.
Additionally speaker 20 had a front mid-to-upper frequency range sound reproduction element 45 mounted above the low-to-mid frequency range element 40. Alternatively, the speaker 20 included a second mid-to-upper range element 46 that was mounted adjacent to the element 44 (FIGS. 3 and 6). Each of the mid-to-upper frequency range elements 45, 46 utilize a solid state piezoelectric transducer. The speaker 20 included a grill 47 overlying the front wall 24 to improve the aesthetics of the enclosure 22 and to provide a dust cover for the front driver 40.
FIG. 2 illustrates a polar graph 48 of the directional performance of the prior art speaker illustrated in FIG. 1. A constant intensity pattern line 50 is illustrated in a 360.degree. polar direction at a frequency of approximately 500 Hz. The polar graph 48 was made about a vertical axis in which the speaker is mounted at the axis. In viewing the pattern 50, one will note a frontal lobe 52 that has a rather narrow directional intensity pattern of less than 120.degree.. Similarly an opposite rear lobe 53 is provided that additionally has an intensity pattern or segment of less than 120.degree.. The pattern line 50 additionally has side lobes 54 and 55 in which there are significant quadrant intensity depressions between the lobs 52-55. An electrical schematic 58 for speaker 20 is shown in FIG. 6. The electrical schematic 58 includes an amplified AC power signal line 60 and a ground or common line 62 for electrically connecting the speaker to an audio amplifier. It should be noted that the mid-to-low range sound reproduction drivers 40 and 42 are mounted in series between the AC signal lines 60 and the common line 62 in which the polarity of the drivers are inverted with the rear driver 42 firstly connected to the power singal line 60 at its positive terminal. An interconnecting line 63 connects the negative terminal of the rear element 42 with the positive terminal of the front element 40. The ground line is connected to the negative terminal of the front element 40. Consequently the AC signal from the amplifier to the front element 40 is first attenuated by the rear element 42.
The mid-to-upper range elements or drivers 44 and 45 are mounted in parallel with both of the low-to-mid range drivers 40 and 42. Time aligned capacitors 64 and 66 are connected in series with the mid-to-upper range drivers 44 and 45 as illustrated in FIG. 6. The mid-to-upper range drivers 44 and 45* have their positive terminals connected to line 60 and their negative terminals connected to the ground or common line 62. Consequently the output of the mid-to-upper range drivers 44 and 45 are time delayed with respect to the low-to-mid frequency range drivers 40 and 42.
Although the speaker 20 operated reasonably well and had some commercial success, applicant has developed a new triangular-shaped speaker having considerably better directional characteristics with reduced power requirements and which is capable of operating more satisfactorily over the wide range of acoustical frequencies from 25 Hz to 2000 Hz.